Radio detecting and ranging (RADAR) devices have been applied to various technical fields. The radar device is mounted on a vehicle to improve the running performance of the vehicle. Such radar devices use electromagnetic waves to detect information about a surrounding environment of the vehicle. In addition, as the information is used in running of the vehicle, the running performance of the vehicle can be improved. To this end, the radar device includes an antenna to transmit and receive electromagnetic waves.
Meanwhile, a vehicle radar may be classified into a long-range radar (LRR) and a short-range radar (SRR). The long-range radar may mainly use frequencies of a 77 GHz band. The short-range radar may mainly use a 24 GHz band.
In general array antennas, it is impossible to arrange a radiator within a half wavelength, which causes the occurrence of the side lobes.